I am a 17 year old boy and i need advice about gain weight during exercise like gym.. my waist size is 26.. and i need to increase my waist.. plz help?

Weight gain: in one area of the body is unlikely. Check w/doctor first to make sure your health is good. Protein powder drinks and higher protein foods can help strengthen muscles throughout the body. Exercise can tone muscles. Celebrate that fact that you are likely healthy and focus as much as possible on how you treat others and cleanliness rather than on body. Peace and good health.

See below: In order to increase your weight you must eat or drink more calories daily than you burn up. But you don't want just more fat on the body so it's important to build muscle also. In order to do this you increase the amount of food you eat daily. Follow a mediterranean type diet and start a strength training muscle building program. For information on diet go to http://bit.ly/1FMQO4d